JP5443268B2 - Method for producing phenolic fiber - Google Patents

Description

The present invention relates to a method for producing a phenolic fibers.

Phenolic fibers are excellent in heat resistance, flame retardancy, and chemical resistance, and have been used for many years in a wide range of fields including general industrial materials where these characteristics are required .

  Phenol-based fibers are conventionally produced by a production method in which a thermoplastic novolac-type phenol resin is melt-spun and then reacted with aldehydes under an acidic catalyst to perform three-dimensional crosslinking and heat infusibilize. (For example, refer to Patent Document 1).

Japanese Patent Publication No. 48-11284

In addition to being completely amorphous, the novolak-type phenol resin used as a raw material has a low degree of polymerization and a high temperature dependency of viscosity. For this reason, a yarn basket obtained by melt spinning a novolac-type phenolic resin rapidly solidifies as the ambient temperature decreases, but has extremely brittle properties. Particularly, the yarn before the crosslinking reaction is fragile. Therefore, for example, when producing other thermoplastic fibers such as polyamide-based fibers and polyester-based fibers, it is possible to add stretching to the yarn string, but when producing phenolic fibers It was impossible to add.
As described above, it is difficult to spin a novolac type phenol resin by a conventional manufacturing method as compared to spinning other thermoplastic resins.

Incidentally, in recent years, when phenolic fibers are used for applications such as woven fabrics, non-woven fabrics, and filters, reduction of pressure loss is required from the viewpoint of high performance. In order to reduce this pressure loss, there is a demand for phenolic fibers (thickened) having a larger fiber diameter than conventional ones.
However, as described above, the yarn before the crosslinking reaction obtained by melt spinning a novolac type phenolic resin is fragile. In addition, fibers obtained by curing (using three-dimensional cross-linking and heat infusibility) the cocoons with aldehydes lose flexibility and become extremely brittle. Therefore, when the diameter of the phenolic fiber is increased by the conventional manufacturing method, the mechanical strength (particularly fiber strength and fiber elongation) required for preparation and spinning of woven fabric, nonwoven fabric, felt, etc. is insufficient. Until now, the limit of increasing the diameter that can withstand practical use has been about a fiber diameter of about 25 μm.

The present invention has been made in view of the above circumstances, and has good heat resistance, flame retardancy and chemical resistance and high mechanical strength, and the fiber diameter has been increased compared to the conventional one. It is an object to provide a method for producing a phenol fiber.

［式中、Ｒ ^１ はヘテロ原子（炭素と水素以外の原子）を有していてもよい炭素数４以上の炭化水素基であり、ＡＯは炭素数２〜４のオキシアルキレン基であり、ｎは平均付加モル数であり０〜１００の数を示す。ジエステルにおいて、複数存在する−（ＡＯ） _ｎ ＯＲ ^１ は互いに同一でも異なっていてもよい。］
In order to solve the above problems, the present invention employs the following configuration.
That is, the method for producing a phenolic fiber of the present invention includes a raw material mixing step in which a phenol resin and phosphate esters are melt- mixed, and a spinning step in which a raw material mixture obtained in the raw material mixing step is spun to obtain a yarn thread possess the door, characterized in that the phosphoric acid esters, containing one or more phosphoric acid ester or salt thereof selected from the group consisting of diesters of mono- and orthophosphoric acid orthophosphoric acid represented by the following general formula And a method for producing phenolic fibers having a fiber diameter exceeding 25 μm .

[Wherein, R ¹ is a hydrocarbon group having 4 or more carbon atoms which may have a hetero atom (atom other than carbon and hydrogen), AO is an oxyalkylene group having 2 to 4 carbon atoms, and n Is the average number of moles added and represents a number from 0 to 100. In the diester, a plurality of — (AO) _n OR ¹ may be the same as or different from each other. ]

According to the method for producing a phenolic fiber of the present invention, a phenolic fiber having good heat resistance, flame retardancy and chemical resistance, high mechanical strength, and a fiber diameter larger than that of the conventional fiber. Can be manufactured .

<Method for producing phenolic fiber>
The method for producing a phenolic fiber of the present invention includes a raw material mixing step of mixing a phenol resin and phosphate esters, and a spinning step of spinning the raw material mixture obtained in the raw material mixing step to obtain a yarn string. .

[Raw material mixing process]
In the raw material mixing step, the phenol resin and phosphate esters are mixed to obtain a raw material mixture.

(Phenolic resin)
As the phenol resin, a novolac type phenol resin obtained by reacting phenols and aldehydes in the presence of an acidic catalyst, or a resol type phenol obtained by reacting phenols and aldehydes in the presence of a basic catalyst Resins, various modified phenolic resins or mixtures thereof can be used.

The phenols are not particularly limited as long as they can be reacted with aldehydes in the presence of an acidic or basic catalyst to obtain each phenol resin. Phenol, o-cresol, m-cresol, p-cresol, 2, 3 -Xylenol, 3,5-xylenol, m-ethylphenol, m-propylphenol, m-butylphenol, p-butylphenol, o-butylphenol, resorcinol, hydroquinone, catechol, 3-methoxyphenol, 4-methoxyphenol, 3-methyl Catechol, 4-methylcatechol, methylhydroquinone, 2-methylresorcinol, 2,3-dimethylhydroquinone, 2,5-dimethylresorcinol, 2-ethoxyphenol, 4-ethoxyphenol, 4-ethylresorcinol, 3-e Xyl-4-methoxyphenol, 2-propenylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 3,4,5-trimethylphenol, 2-isopropoxyphenol, 4-pyropoxyphenol, 2- Allylphenol, 3,4,5-trimethoxyphenol, 4-isopropyl-3-methylphenol, pyrogallol, phloroglicinol, 1,2,4-benzenetriol, 5-isopropyl-3-methylphenol, 4-butoxyphenol 4-t-butylcatechol, t-butylhydroquinone, 4-t-pentylphenol, 2-t-butyl-5-methylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3-phenoxyv Nord, 4-phenoxyphenol, 4-hexyloxyphenol, 4-hexanoylresorcinol, 3,5-diisopropylcatechol, 4-hexylresorcinol, 4-heptyloxyphenol, 3,5-di-t-butylphenol, 3, 5-di-t-butylcatechol, 2,5-di-t-butylhydroquinone, di-sec-butylphenol, 4-cumylphenol, nonylphenol, 2-cyclopentylphenol, 4-cyclopentylphenol, bisphenol A, bisphenol F, etc. Is mentioned.
Among them, phenol, o-cresol, m-cresol, p-cresol, bisphenol A, 2,3-xylenol, 3,5-xylenol, m-butylphenol, p-butylphenol, o-butylphenol, 4-phenylphenol, resorcinol Are preferred, with phenol being most preferred. The said phenols may be used individually by 1 type, and may use 2 or more types together.

Examples of the aldehydes include formaldehyde, trioxane, furfural, paraformaldehyde, benzaldehyde, methyl hemiformal, ethyl hemiformal, propyl hemiformal, salicylaldehyde, butyl hemiformal, phenyl hemiformal, acetaldehyde, propylaldehyde, phenylacetaldehyde, α- Phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p -Ethylbenzaldehyde, pn-butylbenzaldehyde, etc. are mentioned.
Of these, formaldehyde, paraformaldehyde, furfural, benzaldehyde, and salicylaldehyde are preferable, and formaldehyde and paraformaldehyde are particularly preferable. The aldehydes may be used alone or in combination of two or more.

  Examples of the acidic catalyst include hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, succinic acid, butyric acid, lactic acid, benzenesulfonic acid, p-toluenesulfonic acid, boric acid, and salts with metals such as zinc chloride or zinc acetate. It is done. The said acidic catalyst may be used individually by 1 type, and may use 2 or more types together.

  Examples of the basic catalyst include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide; ammonium hydroxide; diethylamine, triethylamine, Examples include amines such as ethanolamine, ethylenediamine, and hexamethylenetetramine. The said basic catalyst may be used individually by 1 type, and may use 2 or more types together.

  Examples of the various modified phenol resins include those obtained by modifying novolac-type or resol-type phenol resins by known techniques such as boron modification, silicon modification, heavy metal modification, nitrogen modification, sulfur modification, oil modification, and rosin modification.

Among the above, as the phenol resin, a novolac type phenol resin and a resol type phenol resin are preferable.
For example, in the case of melt-mixing with phosphate esters and performing melt spinning, which is the most common spinning method in the spinning process described later, either a novolac type or a resol type phenol resin can be used as the phenol resin. However, the resol type is inferior in thermal stability to the novolak type, and the polymerization proceeds easily by heating during melting, so solidification in the melt spinning apparatus is inevitable, and continuous and stable spinning is performed. It is difficult. Therefore, it is particularly preferable to select a novolac type phenol resin in consideration of the ease of the process in industrial production and versatility.
A phenol resin may be used individually by 1 type, and may use 2 or more types together.

(Phosphate esters)
In the present invention, “phosphoric acid” is a general term for various oxo acids produced by hydrolysis of tetraphosphorus decaoxide (P ₄ O ₁₀ ). Orthophosphoric acid and pyrophosphoric acid (diphosphoric acid) represented by the following chemical formulas are used. Acid), triphosphoric acid, tetraphosphoric acid, metaphosphoric acid and the like.

  “Phosphate esters” in the present invention means one in which one or more of —OH in phosphoric acid is substituted with a group represented by the following general formula (1) (phosphate ester) or a salt thereof.

［式中、Ｒ^１はヘテロ原子（炭素と水素以外の原子）を有していてもよい炭素数４以上の炭化水素基であり、ＡＯは炭素数２〜４のオキシアルキレン基であり、ｎは平均付加モル数であり０〜１００の数を示す。］

[Wherein, R ¹ is a hydrocarbon group having 4 or more carbon atoms which may have a hetero atom (atom other than carbon and hydrogen), AO is an oxyalkylene group having 2 to 4 carbon atoms, and n Is the average number of moles added and represents a number from 0 to 100. ]

In the formula (1), as the hydrocarbon group for R ¹ , an alkyl group, an alkenyl group, an aryl group, a group in which part of the hydrogen atom of the alkyl group is substituted with an aryl group, or a part of the hydrogen atom in the alkenyl group Are preferably substituted with an aryl group.
When the hydrocarbon group for R ¹ is an alkyl group or an alkenyl group, R ¹ has more preferably 4 to 22 carbon atoms, and more preferably 8 to 18 carbon atoms.
When the hydrocarbon group of R ¹ is an aryl group, the carbon number of R ¹ is more preferably 6 to 35, and further preferably 6 to 27, specifically phenyl group, naphthyl group, benzyl group, tolyl group. And xylyl group.
In any case of the hydrocarbon group of R ¹ , if the carbon number of R ¹ exceeds the upper limit value, the compatibility with the phenol resin tends to decrease. When R ¹ is an aryl group, the compatibility with the phenol resin is relatively better than when R ¹ is an alkyl group or an alkenyl group.

In said Formula (1), AO is a C2-C4 oxyalkylene group, and an oxyethylene group, an oxypropylene group, and an oxybutylene group are mentioned. Note that an oxygen atom in the oxyalkylene group is bonded to the phosphorus atom.
In said Formula (1), n is a number of 0-100, 0-50 are preferable and 0-10 are more preferable.

Among these, as phosphate esters, since mechanical strength tends to increase particularly when a large-diameter phenolic fiber is used, at least one of —OH in orthophosphoric acid is a group represented by the above formula (1). Those substituted with (orthophosphate) or salts thereof are preferred.
Specific examples of the orthophosphoric acid ester include monoesters, diesters, and triesters of orthophosphoric acid represented by the following general formula. Of these, monoesters and diesters of orthophosphoric acid are preferable.

［式中、Ｒ^１、ＡＯ、ｎはそれぞれ前記と同じである。ジエステルとトリエステルにおいて、複数存在する−（ＡＯ）_ｎＯＲ^１は互いに同一でも異なっていてもよい。］

[Wherein, R ¹ , AO and n are the same as defined above. In the diester and triester, a plurality of — (AO) _n OR ¹ may be the same as or different from each other. ]

Examples of the phosphate ester salt include alkali metal salts, alkaline earth metal salts, ammonium salts and amine salts of phosphate esters.
Phosphoric esters may be used alone or in combination of two or more.

(mixture)
In the raw material mixing step, when the phenol resin and the phosphate ester are mixed, the amount of the phenol resin used is such that the ratio of the phenol resin in the obtained raw material mixture is 55 to 99.9% by mass. The amount is preferably 70 to 99% by mass, and more preferably 85 to 95% by mass.
The amount of phosphate esters used is preferably such that the proportion of phosphate esters in the resulting raw material mixture is 0.1 to 45% by mass, and 1 to 30% by mass. It is more preferable that the amount is 5 to 15% by mass. If the ratio of phosphate esters is equal to or more than the preferred lower limit, the effect of improving the mechanical strength when the phenolic fiber is increased in diameter is likely to be obtained. On the other hand, if the ratio of the phenol resin is equal to or less than the preferable upper limit value, it is easy to maintain characteristics such as heat resistance, flame retardancy, and chemical resistance of the phenol fiber.

  Examples of the method of mixing the phenol resin and the phosphate ester include a method of melt-mixing both, a method of dissolving and mixing both using a solvent, and the like. Among these, from the viewpoint of complexity of the process, environmental load, and economical efficiency, a method of melt-mixing both is preferable.

As an example of the melt mixing of the phenol resin and the phosphate ester, there is a method of heating and kneading both.
The heating and kneading of the phenol resin and the phosphate ester can be performed using a known kneading apparatus. Examples of the kneading apparatus include an extruder-type kneader, a mixing roll, a Banbury mixer, and a high-speed biaxial continuous mixer. Can be mentioned.
What is necessary is just to select the temperature of heat-kneading suitably with the property etc. of a raw material, 200 degrees C or less is preferable and 140-180 degreeC is more preferable. By setting the temperature of the heat-kneading to a preferable upper limit value or less, thermal denaturation and deterioration due to exposure of the raw material to a high temperature can be easily suppressed. By setting the temperature of the heat-kneading to a preferable lower limit value or more, it becomes possible to efficiently mix both.
The heat kneading time is preferably 15 minutes or more, more preferably 30 to 120 minutes. By setting the heating and kneading time to be equal to or more than the preferable lower limit value, it becomes possible to mix both more uniformly. By making the time of heating and kneading below the preferable upper limit, it is easy to suppress thermal denaturation and deterioration of the raw material.

In a method in which a phenol resin and phosphate esters are dissolved and mixed using a solvent, a raw material mixture is obtained by dissolving and mixing both in a solvent that can dissolve both, and then evaporating and removing the solvent.
As a solvent that can dissolve both, a solvent selected from a ketone solvent, an ether solvent, a nitrogen-containing solvent, a hydrocarbon solvent, an ester solvent, an alcohol solvent, or a mixture of two or more of them is used. it can.
In the dissolution and mixing of the phenol resin and the phosphate ester, it is preferable to gradually add the phenol resin and the phosphate ester while stirring the solvent. At that time, it is effective to heat the phenol resin or phosphate ester if it is difficult to dissolve in the solvent. Further, by applying pressure, it is possible to heat the solvent at a temperature higher than the boiling point of the solvent at normal pressure, which is further effective. However, since exposure to the raw material at a high temperature may cause thermal denaturation and deterioration, it is preferable to perform the heating limitedly until the raw material is completely dissolved.

 The concentration of the phenolic resin and phosphate ester dissolved in the solvent is not particularly limited, and may be appropriately set in consideration of the properties of the raw material and the spinning method in the subsequent spinning step. In addition, from the point that much time and energy are required to recover the solvent to be removed by evaporation, it is preferable to set the concentration of the phenol resin and the phosphate ester as high as possible in consideration of their respective solubilities.

As a method of mixing the phenol resin and the phosphate ester, a method other than the above-mentioned melt mixing and dissolution mixing may be used. For example, when a dry spinning, wet spinning or dry / wet spinning method is used as a spinning method in the subsequent spinning step, a raw material mixture obtained by dissolving and mixing both in a solvent capable of dissolving both phenolic resin and phosphate ester A solution may be prepared. The raw material mixture solution can be used directly as a stock solution for spinning.
In addition, if the raw material does not deteriorate at the temperature during the synthesis reaction without inhibiting the synthesis reaction of the phenol resin, both can be added by adding phosphate esters during the phenol resin synthesis reaction. It is also effective to mix.

In the raw material mixing step, even if any method is used to obtain the raw material mixture, known additives, plasticizers, compatibilizers, antioxidants, ultraviolet absorbers, penetrants, if necessary. Thickeners, antifungal agents, dyes, pigments, fillers and the like may be used.
In particular, when the phenol resin and the phosphate ester are melt-mixed and the melt viscosity of the phosphate ester is extremely different from that of the phenol resin, it is preferable to use a compatibilizing agent. This can prevent separation during spinning.

[Spinning process]
In the spinning step, the raw material mixture obtained in the raw material mixing step is spun to obtain a yarn.
As the spinning method, a known method can be appropriately selected in view of the properties of the raw material mixture, and examples thereof include wet spinning, dry spinning, dry / wet spinning, melt spinning, gel spinning, and liquid crystal spinning. Of these, melt spinning is preferred because of the simplicity of the apparatus and economic advantages.

When melt spinning is used as a spinning method, a general melt spinning apparatus can be used.
As a melting apparatus of the melt spinning apparatus, a grid melter type, a single screw extruder method, a twin screw extruder method, a tandem extruder method, or the like can be used.
In order to prevent oxidation of the melted raw material mixture, nitrogen replacement in the melt spinning apparatus may be performed, or an operation of removing a trace amount of residual solvent or monomers using an extruder equipped with a vent. May be performed.

In melt spinning, the temperature condition is preferably 120 to 200 ° C, more preferably 140 to 170 ° C. By setting the temperature condition to be equal to or higher than the preferable lower limit, spinning can be performed efficiently. By setting the temperature condition to a preferable upper limit value or less, thermal denaturation and deterioration are easily suppressed, and the phenol resin and the phosphate ester are difficult to separate.
As the spinneret, a normal one can be used, and the hole diameter is preferably 0.05 mm or more and less than 1 mm, more preferably 0.1 mm or more and less than 0.5 mm, and the (length L / diameter D) of the capilla part is 0. 5 or more and less than 10 is preferable, and 1 to 5 is more preferable. By setting the pore diameter and L / D within the above preferred ranges, stable spinning can be achieved.
In the case of a special fiber manufacturing method (for example, in the case of side-by-side conjugate fiber, core-sheath type conjugate fiber, sea-island type conjugate fiber, etc.), a conjugate base that combines a side-by-side type or seascore type or a third component polymer. Can also be used.

The spinning speed is preferably 15 m / min or more and less than 3000 m / min, more preferably 30 m / min or more and less than 2000 m / min, and further preferably 50 m / min or more and less than 1600 m / min.
By setting the spinning speed to a preferable lower limit value or more, spinning can be performed efficiently. By making the spinning speed less than the preferred upper limit, the occurrence of yarn breakage during spinning can be suppressed.

[Curing process]
In the method for producing a phenolic fiber of the present invention, it is preferable to have a curing step of curing the yarn obtained in the spinning step. By curing the yarn thread in the curing step, the phenol resin portion is mainly cross-linked, so that the mechanical strength of the thickened phenolic fiber is increased.

  When a novolac type phenol resin is used as a raw material phenol resin, the method of curing the yarn obtained in the spinning step is to immerse the staple or tow-shaped material in a treatment liquid in a reaction vessel and batch A method of curing by a formula, a method of curing a bobbin or skein processed with a processing liquid, a method of continuously curing a tow-shaped processed with a processing liquid, etc. Is mentioned.

The treatment liquid consists of a catalyst and aldehydes.
Examples of the catalyst include hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, succinic acid, butyric acid, lactic acid, benzenesulfonic acid, p-toluenesulfonic acid, boric acid, zinc chloride, zinc acetate, a salt with a metal, or a mixture thereof. Acidic catalysts of sodium hydroxide, alkali metal hydroxides such as lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide, ammonium hydroxide, diethylamine, triethylamine, triethanolamine, Examples include basic catalysts such as amines such as ethylenediamine and hexamethylenetetramine, or mixtures thereof. A catalyst may be used individually by 1 type and may use 2 or more types together.

Examples of aldehydes include formaldehyde, trioxane, furfural, paraformaldehyde, benzaldehyde, methyl hemiformal, ethyl hemiformal, propyl hemiformal, salicylaldehyde, butyl hemiformal, phenyl hemiformal, acetaldehyde, propylaldehyde, phenylacetaldehyde, α-phenylpropylene. Aldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m -Methylbenzaldehyde, p-methylbenzaldehyde, p-d Tilbenzaldehyde, pn-butylbenzaldehyde and the like can be used.
Of these, formaldehyde, paraformaldehyde, furfural, benzaldehyde, and salicylaldehyde are preferable, and formaldehyde and paraformaldehyde are particularly preferable. Aldehydes may be used alone or in combination of two or more.

Curing is preferably performed in the liquid phase by heating at a temperature of 60 ° C. or higher and lower than 110 ° C. for 3 hours or longer and less than 30 hours. Moreover, in this invention, you may harden | cure by heating in a gaseous phase.
Furthermore, after the heating, it is possible to perform a known curing treatment such as washing with water and drying and further curing by heating at a temperature of 100 to 300 ° C. in an inert gas such as nitrogen, helium, carbon dioxide. By this curing treatment, the phenol resin portion in the yarn can be cross-linked, and a phenol fiber having sufficient strength can be obtained.

On the other hand, when a resol type phenol resin is used as a raw material phenol resin, the yarn string can be cured by heat treatment by a wet heat method or a dry heat method.
As for the heat treatment conditions, the temperature is preferably 100 to 220 ° C, more preferably 120 to 180 ° C, and the treatment time is preferably 5 to 120 minutes, more preferably 20 to 60 minutes.

In the method for producing phenolic fibers of the present invention, phenolic fibers having high mechanical strength are produced.
Specifically, a phenol fiber having a tensile strength of 12 kg / mm ² or more can be easily obtained. Moreover, a phenol fiber having an elongation of 8% or more can be easily obtained.
Here, “tensile strength” and “elongation” indicate values measured by methods according to JIS L-1015, respectively.

  And the manufacturing method of the phenol type fiber of this invention can manufacture the phenol type fiber by which the fiber diameter was enlarged compared with the past. Specifically, phenolic fibers having a fiber diameter exceeding 25 μm can be easily obtained.

In the method for producing a phenolic fiber of the present invention described above, a phenolic fiber is obtained by spinning a raw material mixture obtained by mixing a phenol resin and a phosphate ester. By using the raw material mixture, the reason is not clear, but the mechanical strength is increased by the interaction between the phenol resin and the phosphate ester. It was possible to produce a thickened phenolic fiber that was difficult.
In addition, the phenolic fiber produced by the method for producing a phenolic fiber of the present invention has good heat resistance, flame retardancy, and chemical resistance as in the conventional phenolic fiber.
In addition, the method for producing a phenolic fiber of the present invention is merely mixing a phosphate ester used newly with a phenol resin, and there is no complication in the process. System fibers can be produced.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
In this example, the fiber diameter, fineness, tensile strength, tensile modulus, elongation, and specific surface area were measured by the following methods. In addition, heat resistance, flame retardancy and chemical resistance were evaluated by the following methods, respectively.

[Fiber diameter]
The fiber diameter (μm) of the phenolic fiber was measured using a VK-8500 laser microscope manufactured by Keyence Corporation.

[Fineness]
The fineness (denier) of the phenolic fiber was measured using a DC11B denier computer manufactured by Search Corporation.

[Tensile strength]
The tensile strength (kg / mm ² ) of the phenol fiber was measured by a method based on JIS L-1015 using an RTG-1210 Tensilon universal testing machine manufactured by A & D Co., Ltd.

[Tensile modulus]
The tensile modulus (kg / mm ² ) of the phenol fiber was measured by a method based on JIS L-1015 using an RTG-1210 Tensilon universal testing machine manufactured by A & D Co., Ltd.

[Elongation]
The elongation (%) of the phenol fiber was measured by a method based on JIS L-1015 using an RTG-1210 Tensilon universal testing machine manufactured by A & D Co., Ltd.

[Heat-resistant]
The heat resistance of the phenol fiber is determined by measuring the tensile strength by the above method after exposing the obtained phenol fiber to air at 150 ° C. and 180 ° C. for 100 hours, respectively. (%) Was evaluated by calculating.
Strength retention (%) = (Tensile strength after exposure / Tensile strength before exposure) × 100

[Flame retardance]
The flame retardancy of the phenol fiber was evaluated by measuring the limiting oxygen index (LOI) of the obtained phenol fiber by a method based on JIS L-1091. Generally, if the LOI value is 28 or more, it is determined that the material has flame retardancy.

[chemical resistance]
The chemical resistance of the phenol fiber is obtained by applying the obtained phenol fiber to various chemicals (36 mass% hydrochloric acid, 25 mass% aqueous ammonia, acetone, N, N-dimethylformamide (DMF)) at 25 ° C., respectively. After immersion for 100 hours, the tensile strength was measured by the above method, and the strength retention (%) was calculated in the same manner as in the heat resistance evaluation.

<Production example of phenol fiber>
Using the phenol resin and phosphate esters shown below, phenolic fibers were produced according to the respective production examples.

-Phenol resin The novolak type phenol resin synthesize | combined as follows was used for the phenol resin.
[Synthesis of phenolic resin]
1000 g of phenol, 733 g of 37% by mass formalin and 5 g of oxalic acid were charged into a reaction vessel equipped with a reflux condenser, heated from room temperature to 100 ° C. over 40 minutes, and further reacted at 100 ° C. for 4 hours. And dehydrated and concentrated, and then cooled to obtain a novolak type phenol resin.

-Phosphate ester Phosphate ester (1) and phosphate ester (2) shown below were used for phosphate ester.
Phosphate ester (1): Phosphanol SM-172 (trade name, manufactured by Toho Chemical Industry Co., Ltd., the mass ratio of the monoester of the following formula (IA) to the diester of the following formula (IB) is (IA) / (IB) = 1/1 mixture).
Phosphate ester (2): Phosphanol RP-710 (trade name, manufactured by Toho Chemical Industry Co., Ltd., polyoxyethylene (average addition mole number 6) phenyl ether phosphoric acid. Other than monoester of the following formula (II) A mixture containing a diester and a triester).

Example 1
Raw material mixing process:
450 g of novolak-type phenol resin and 50 g of phosphoric acid ester (1) are put into a twin-screw kneader (high-speed twin-screw continuous mixer) and kneaded (melted and mixed) at 150 ° C. for 50 minutes. A block was obtained.

Spinning process:
Next, this block-like product is coarsely pulverized and melted at 180 ° C. using a melt spinning apparatus (grid melter type), and the melt obtained by the melting has a pore diameter of 0.1 mm maintained at 160 ° C., A yarn was obtained by spinning (melt spinning) at a spinning speed of 75 m / min while maintaining a constant discharge rate from a spinneret having a length L / diameter D = 3 and 10 holes.

Curing process:
The yarn thread obtained in the spinning process was cut into a length of 51 mm, placed in a flask, immersed in an aqueous solution of 14% by mass hydrochloric acid and 8% by mass formaldehyde for 30 minutes at room temperature, and then heated to 98 ° C. in 2 hours. Further, curing was carried out by holding at 98 ° C. for 2 hours.

  Next, the cured product obtained in the curing step was taken out from the flask and thoroughly washed with water, and then neutralized with a 3% by mass aqueous ammonia solution at 60 ° C. for 30 minutes. Thereafter, it was thoroughly washed with water again and dried at 90 ° C. for 30 minutes to obtain a phenol fiber.

(Example 2)
A phenolic fiber was obtained in the same manner as in Example 1 except that 50 g of phosphate ester (2) was used instead of 50 g of phosphate ester (1) in the raw material mixing step.

(Comparative Example 1)
Phenol fibers were obtained in the same manner as in Example 1 except that in the raw material mixing step, 500 g of novolac type phenol resin was used instead of 450 g of novolac type phenol resin and 50 g of phosphoric ester (1).

  Results of measurement of fiber diameter, fineness, tensile strength, tensile modulus, elongation, strength retention (heat resistance), LOI (flame resistance), strength retention (chemical resistance) of the obtained phenolic fiber Is shown in Table 1.

From the results in Table 1, it can be seen that the phenolic fibers produced in Examples 1 and 2 have high tensile strength and high elongation, regardless of whether the fiber diameter is increased.
Moreover, it turns out that the phenol-type fiber each manufactured in Example 1, 2 has favorable heat resistance, a flame retardance, and chemical resistance.
On the other hand, the phenolic fiber produced in Comparative Example 1 cannot be used practically because of its low tensile strength and extremely low elongation.

Claims (2)

A raw material mixing step in which a phenol resin and phosphate esters are melt- mixed;
By spinning the resulting raw material mixture in the raw material mixing step possess a spinning step of obtaining a ItoJo,
The fiber diameter, wherein the phosphoric acid ester comprises one or more phosphoric acid esters or salts thereof selected from the group consisting of orthophosphoric acid monoesters and orthophosphoric acid diesters represented by the following general formula: Process for producing a phenolic fiber having a thickness exceeding 25 μm .

[Wherein, R ¹ is a hydrocarbon group having 4 or more carbon atoms which may have a hetero atom (atom other than carbon and hydrogen), AO is an oxyalkylene group having 2 to 4 carbon atoms, and n Is the average number of moles added and represents a number from 0 to 100. In the diester, a plurality of — (AO) _n OR ¹ may be the same as or different from each other. ] The method for producing a phenolic fiber according to claim 1, further comprising a curing step of curing the yarn obtained in the spinning step.